1. Field
The present invention relates to a lithographic apparatus and a method for manufacturing a device.
2. Related Art
A lithographic apparatus is a machine that applies a desired pattern onto a substrate or part of a substrate. A lithographic apparatus can be used, for example, in the manufacture of flat panel displays, integrated circuits (ICs) and other devices involving fine structures. In a conventional apparatus, a patterning device, which can be referred to as a mask or a reticle, can be used to generate a circuit pattern corresponding to an individual layer of a flat panel display (or other device). This pattern can be transferred on (part of) the substrate (e.g., a glass plate), e.g., via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate.
Instead of a circuit pattern, the patterning means can be used to generate other patterns, for example a color filter pattern or a matrix of dots. Instead of a mask, the patterning device can comprise a patterning array that comprises an array of individually controllable elements. The pattern can be changed more quickly and for less cost in such a system compared to a mask-based system.
A flat panel display substrate can be rectangular in shape. Lithographic apparatus designed to expose a substrate of this type can provide an exposure region that covers a full width of the rectangular substrate, or which covers a portion of the width (for example half of the width). The substrate can be scanned underneath the exposure region, while the mask or reticle is synchronously scanned through the projection beam. In this way, the pattern is transferred to the substrate. If the exposure region covers the full width of the substrate then exposure can be completed with a single scan. If the exposure region covers, for example, half of the width of the substrate, then the substrate can be moved transversely after the first scan, and a further scan is typically performed to expose the remainder of the substrate.
In the case where an array of individually controllable elements is used to generate the pattern on the substrate, the speed at which rasterized pattern data can be processed and passed to the array of individually controllable elements as a suitable control signal is a factor critical to the performance of the lithographic apparatus. A significant proportion of the overall cost of the apparatus is associated with the computational hardware provided to carry out this processing. The demands on computational hardware are particularly severe where processing has to be carried out at the same time as the substrate is being exposed (sometimes referred to as “on-the-fly” processing).
The pattern data can be exposed by a plurality of arrays of individually controllable elements, and each of these can be provided with separate optics and data processing hardware (all or part of each such assembly is sometimes referred to as an “optical column” or “optical engine”). Each optical column can be assigned predominantly to a particular strip of the substrate to be exposed and the data processing tasks can be split accordingly.
In order to be able to cope with variety in pattern layouts, each optical engine has to be provided with sufficient processing capacity to cope with the worse case scenario for the strip of pattern that it is to deal with, which is expensive.
Therefore, what is needed is a system and method where data processing is more efficiently managed.